This invention provides a boiler structure for burning solid fuels, although it could burn liquid or gaseous fuels. The boiler is intended to recover a much higher proportion of the heat of combustion that is recovered in similar prior art boilers, and seeks to discharge the gases resulting from combustion into the atmosphere at a much lower temperature than is done in the prior art. The boiler is particularly useful for burning wood, such as logs, on a farm to produce hot water that can be circulated through heat exchangers to achieve, for example space heating of living quarters and drying of crops such as tobacco.
The prior art patents on boiler structures used for similar purposes, i.e. to produce hot water or steam, include U.S. Pat. No. 953,023 to Doran which shows a water boiler structure having a fire box at one end which is partly surrounded by water jackets communicating with the boiler and which has a large diameter tube extending from the fire box through the water filled boiler to conduct hot gases therethrough at a rate which is controlled by a valve 30 beyond the fire box. U.S. Pat. No. 220,106 to Allen, and U.S. Pat. No. 1,446,145 to Allan, and U.S. Pat. No. 112,049 to Judge, and U.S. Pat. No. 347,463 to Boyer also show boiler structures having tubes for conducting hot gases through the water in the boiler from a fire box.
The prior art further shows a broad idea of using water filled tubes serving as a grate for supporting the burning fuel, as illustrated in U.S. Pat. No. 4,154,210 to Jaymes, and the above mentioned patents to Doran, Allan and Judge.
The broad idea of using water jackets to partially surround the fire box is shown in U.S. Pat. No. 132,129 to Backus, U.S. Pat. No. 442,563 to Wells, and the above mentioned patents to Doran and Boyer.
However, it is believed that these patents and the other patents of the prior art do not show boiler structures capable of converting the heat of combustion to heat water as efficiently as the boiler structure of the present invention.